Bharat stage emission standards

Bharat stage emission standards are emission standards instituted by the Government of India to regulate the output of air pollutants from compression ignition engines and spark-ignition engines equipment, including motor vehicles. The standards and the timeline for implementation are set by the Central Pollution Control Board under the Ministry of Environment, Forest and Climate Change.
The standards, based on European regulations, were first introduced in 2000. Progressively stringent norms have been rolled out since then. All new vehicles manufactured after the implementation of the norms have to be compliant with the regulations. Since October 2010, Bharat Stage III norms have been enforced across the country. In 13 major cities, Bharat Stage IV emission norms have been in place since April 2010 and it has been enforced for entire country since April 2017. In 2016, the Indian government announced that the country would skip the BS V norms altogether and adopt BS VI norms by 2020. In its recent judgment, the Supreme Court has banned the sale and registration of motor vehicles conforming to the emission standard Bharat Stage IV in the entire country from 1 April 2020.
On 15 November 2017, the Petroleum Ministry of India, in consultation with public oil marketing companies, decided to bring forward the date of BS VI grade auto fuels in NCT of Delhi with effect from 1 April 2018 instead of 1 April 2020. In fact, Petroleum Ministry OMCs were asked to examine the possibility of introduction of BS VI auto fuels in the whole of NCR area from 1 April 2019. This huge step was taken due to the heavy problem of air pollution faced by Delhi which became worse around 2019. The decision was met with disarray by the automobile companies as they had planned the development according to roadmap for 2020.
The phasing out of 2-stroke engine for two wheelers, the cessation of production of the Maruti 800, and the introduction of electronic controls have been due to the regulations related to vehicular emissions.
While the norms help in bringing down pollution levels, it invariably results in increased vehicle cost due to the improved technology and higher fuel prices. However, this increase in private cost is offset by savings in health costs for the public, as there is a lower amount of disease-causing particulate matter and pollution in the air. Exposure to air pollution can lead to respiratory and cardiovascular diseases, which is estimated to be the cause for 620,000 early deaths in 2010, and the health cost of air pollution in India has been assessed at 3% of its GDP.
In Delhi-NCR, vehicle movement is regulated under the air-quality based Graded Response Action Plan. In 2025, the Commission for Air Quality Management enforced GRAP Stage III measures, restricting the entry of BS-III petrol and BS-IV diesel vehicles across the region to curb rising pollution levels.

Motor vehicles

To regulate the pollution emitted by cars and two-wheelers, the Government of India has placed forth regulations known as Bharat Stage Emission Standards. The Central Government has mandated that every vehicle manufacturer, both two-wheels and four-wheels, ought to manufacture, sell and register solely BS6 vehicles from 1 April 2020.
Both BSIV and BSVI area unit emission norms that set the most permissible levels for pollutants emitting from an automotive or a two-wheeler exhaust. Compared to the BS4, BS6 emission standards area unit stricter, whereas makers use this variation to update their vehicles with new options and safety standards, the largest or the numerous modification comes within the type of stricter permissible emission norms.
The below table offers Associate in Nursing insight into the modification within the permissible emission levels of BS6 vehicles compared to BS4 vehicles:

Fuel type	Pollutant Gases	BS6	BS4
Petroleum Distillate Vehicle	Nitrogen Oxide Limit	60 mg	80 mg
	Particulate Matter Limit	4.5 mg/km	-
Diesel Fuel Vehicle	Nitrogen Oxide Limit	80 mg	250 mg
	Particulate Matter Limit	4.5 mg/km	25 mg
	HC + NOx	170 mg/km	300 mg

These area unit emission standards set by Bharat Safety Emission commonplace to manage the output of pollutants from vehicles plying on the road. The Central Pollution Control Board, under the Ministry of Environment, Forest and Climate Change, sets the permissible pollution levels and timeline to implement an equivalent by vehicle makers.
The abbreviation of Bharat Stage is 'BS' suffixed with the iteration of the stage of emission norms, similar to how European emissions standards are named. The initial BSI standard was first introduced in mid 1999, with the second and third iteration first introduced in mid 2000 and 2005 named BSII and BSIII, respectively.
The fourth iteration BSIV or BS4 was introduced in 2017, and therefore the delay between the introduction of BS3 and BS4 resulted in the fast-tracking of the BSVI or BS6 standards by skipping the BSV norms. Each of the regulations have stricter emission standards compared to its predecessors.

History

The first emission norms were introduced in India in 1991 for petroleum distillate, and 1992 for diesel vehicles. These were followed by making the Catalytic converter mandatory for petrol vehicles and the introduction of unleaded petrol in the market.
On 29 April 1999, the Supreme Court of India ruled that all vehicles in India have to meet Euro I or India 2000 norms by 1 June 1999 and Euro II will be imperative in the NCR by 1 April 2000. Car makers were not prepared for this transition and in a subsequent judgement the implementation date for Euro II was not enforced.
In 2002, the Indian Government accepted the report submitted by the Mashelkar committee. The committee proposed a road map for the roll-out of Euro based emission norms for India. It also recommended a phased implementation of future norms with the regulations being implemented in major cities first and extended to the rest of the country after a few years.
Based on the recommendations of the committee, the National Auto Fuel policy was announced officially in 2003. The roadmap for implementation of the Bharat stage norms were laid out until 2010. The policy also created guidelines for auto fuels, reduction of pollution from older vehicles and R&D for air quality data creation and health administration.

Background information

The above standards apply to all new 4-wheeled vehicles sold and registered in the respective regions. In addition, the National Auto Fuel Policy introduces certain emission requirements for interstate buses with routes originating or terminating in Delhi or the other 10 cities.
Progress of emission standards for 2-and 3-wheeled vehicles:

Standard	Reference	Date
Bharat Stage II	Euro 2	1 April 2000
Bharat Stage III	Euro 3	1 April 2010
Bharat Stage IV	Euro 4	1 April 2017
Bharat Stage VI	Euro 6	1 April 2020 with mandate

In order to comply with the BSIV norms, 2- and 3-wheeler manufacturers will have to fit an evaporative emission control unit, which should lower the amount of fuel that is evaporated when the motorcycle is parked.

Trucks and buses

Emission standards for new heavy-duty diesel engines—applicable to vehicles of GVW > 3,500 kg—are listed in Table 3.
More details on Euro I–III regulations can be found in the EU heavy-duty engine standards.

Light-duty diesel vehicles

Emission standards for light-duty diesel vehicles are summarised in Table 4. Ranges of emission limits refer to different classes of light commercial vehicles; comparable to EU light-duty vehicle emission standards. The lowest limit in each range applies to passenger cars.
The test cycle has been the ECE + EUDC for low power vehicles. Before 2000, emissions were measured over an Indian test cycle.
Engines for use in light-duty vehicles can be also emission tested using an engine dynamo-meter. The respective emission standards are listed in Table 5.

Light-duty petrol vehicles

4-wheeled vehicles

Emissions standards for petrol vehicles are summarised in Table 6. Ranges of emission limits refer to different classes of light commercial vehicles. The lowest limit in each range applies to passenger cars.
Petrol vehicles must also meet an evaporative limit of 2 g/test.

2- and 3-wheeled vehicles

Emission standards for 2- and 3-wheeled petrol vehicles are listed in the following tables.

Year	CO	HC	HC+NO_x
1991	12–30	8–12	–
1996	6.75	–	5.40
2000	4.00	–	2.00
2005	2.25	–	2.00
2010-04	1.25	–	1.25

Year	CO	HC	HC+NO_x
1991	12–30	8–12	–
1996	5.50	–	3.60
2000	2.00	–	2.00
2005	1.5	–	1.5
2010-04	1.0	–	1.0

Year	CO	HC+NO_x	PM
2005-04	1.00	0.85	0.10
2010-04	0.50	0.50	0.05

Overview of the emission norms in India

1991 – Idle CO limits for petrol vehicles and free acceleration smoke for diesel vehicles, mass emission norms for petrol vehicles.
1992 – Mass emission norms for diesel vehicles.
1996 – Revision of mass emission norms for petrol and diesel vehicles, mandatory fitment of catalytic converter for cars in metros on unleaded petrol.
1998 – Cold start norms introduced.
2000 – India 2000 norms, modified IDC, Bharat Stage II norms for Delhi.
2001 – Bharat Stage II norms for all metros, emission norms for CNG and LPG vehicles.
2003 – Bharat Stage II norms for 13 major cities.
2005 – From 1 April, Bharat Stage IV norms for 13 major cities.
2010 – Bharat Stage IV emission norms for 2-wheelers, 3-wheelers and 4-wheelers for the entire country, whereas Bharat Stage IV for 13 major cities for only 4-wheelers. Bharat Stage IV also has norms on OBD.
2017 – Bharat Stage IV norms for all vehicles.
2018 - Bharat Stage VI fuel norms from 1 April 2018 in Delhi instead of 2020.
2020 – Bharat Stage VI fuel norms from 1 April 2020 nationwide switching India to world's cleanest diesel and petrol.
2023 - Bharat Stage VI Second Phase Fuel norms from 1 April 2023 have only Petrol also called RDE norms with e20 fuels.